This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A039009 #14 Jun 20 2021 16:17:16 %S A039009 1,2,4,6,7,9,11,12,14,15,21,22,24,28,31,32,34,36,37,39,40,46,47,49,53, %T A039009 56,57,59,61,62,64,65,71,72,74,76,77,79,80,85,95,103,106,107,109,111, %U A039009 112,114,115,121,122,124,133,138,141,142,144,148,153,156,157,159,161 %N A039009 Numbers whose base-5 representation has the same number of 0's and 3's. %H A039009 Daniel Starodubtsev, <a href="/A039009/b039009.txt">Table of n, a(n) for n = 1..10000</a> %t A039009 Select[Range[200],DigitCount[#,5,0]==DigitCount[#,5,3]&] (* _Harvey P. Dale_, Dec 10 2015 *) %Y A039009 Cf. A007091. %K A039009 nonn,base,easy %O A039009 1,2 %A A039009 _Olivier Gérard_